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An alum dose of 65 mg/L is considered to be an over dose. At this point in time, only the data for the Floc blanket on high has been collected. a slight overdose. Image Modified
Figure 1: Effluent Turbidity vs. Time, Floc Blanket on Low, Alum dose = 65 mg/L
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Figure 2: Effluent Turbidity vs. Time, Flock Blanket on High, Alum dose = 65 mg/L

Conclusions

The higher alum dose yielded a higher average turbidity for all capture velocities. At 5 and 10 m/day the effluent turbidity was under 1 NTU, however at 15 and 20 m/day the average effluent turbidity was higher and above 1 NTU. It was expected that higher capture velocities would yield a higher effluent turbidityFor the floc blanket at both the lower and higher levels, the capture velocity of .058 mm/s produces a lower effluent turbidity than the Vc = .116 mm/s, and Vc = .174 produces a higher effluent turbidity than Vc = .116 mm/s, which is expected.  However, Vc = .231 mm/s produces a lower effluent turbidity than Vc = .174 mm/s.  This is not consistent with what should have happened, and cannot be explained by floc particles rolling up the settler tube into the effluent.